My mr report says "there was observed increases minimal subchondral sclerosis at sacroiliac joint forming surfaces of bone." is it important?

Yes and No: This is a finding that can confuse both physicians and patients alike. Typically sacroiliac pain is a constellation of symptoms and one aspect of the pain issue in this area involves the actual bone on bone interaction. The other aspects of this problem stems from the ligaments which attach the two bones on the posterior side and the joint capsule on the anterior side which all cause pain.

No: 'minimal sclerosis' probably means nothing.

Not really: The observation in the report is probably within normal variation for a patient of your age. As long as you have no symptoms or pain which relates to your sacroiliac joints, you do not have to worry. If you have any problems in the future, do yourself a favor and avoid Doctors who list all sorts of "findings" in their reports, but do not tell you the significance of each one of their findings.